@book { MarketingbeiTierundWildparks,
    title = "Marketing bei Tier- und Wildparks",
    author = "Linda {Keißner}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836626392",
    url = "https://m.diplom.de/document/226583"
}